Method and system for carbon capture and recycling

ABSTRACT

A method for carbon capture and recycling, the method including the steps of: (i) Capturing CO2 from at least one CO2 containing input; (ii) Producing a CO2 feed stream from the captured CO2; and (iii) Reacting the CO2 feed stream with a H2 feed stream to produce a methane containing output.

RELATED APPLICATIONS

The present invention is a U.S. National Stage under 35 USC 371 patentapplication, claiming priority to Serial No. PCT/AU2017/050613, filed on16 Jun. 2017; which claims priority of AU 2016902386, filed on 18 Jun.2016, the entirety of both of which are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a method and system for carbon captureand recycling, and in particular methods and systems for capturing CO₂and producing methane, acetylene and/or other hydrocarbons.

BACKGROUND

The reference in this specification to any prior publication (orinformation derived from it), or to any matter which is known, is not,and should not be taken as an acknowledgment or admission or any form ofsuggestion that the prior publication (or information derived from it)or known matter forms part of the common general knowledge in the fieldof endeavour to which this specification relates.

Climate change is an important issue on the agenda of governmentsworldwide. It is proposed that climate change is accelerated by humanproduction of “greenhouse gases”. Greenhouse gases are those which gettrapped in the atmosphere and enhance the “greenhouse effect”. In thegreenhouse effect, heat is trapped from escaping the earth due to abuild up of the greenhouse gases in the atmosphere. Therefore, inseeking to address climate change, several approaches look to reducegreen house gas emissions.

Carbon dioxide (CO₂) is one green house gas where emissions aretargeted. Several approaches have been developed to capture and/orreduce CO₂ emissions. One such approach is carbon capture and storagewhereby CO₂ is captured (e.g. from air, flue gas etc.) and then storedin selected geological rock formations below the earths surface. It willbe appreciated that carbon capture and storages can be expensive, andfurthermore, no usable products/outputs are produced from the capturedCO₂, it is simply captured and stored.

The present invention seeks to provide an approach to reducing CO₂emissions that also provides industrially applicable products.

SUMMARY OF THE INVENTION

In one broad form, the present invention provides a method for carboncapture and recycling, the method including the steps of: (i) CapturingCO₂ from at least one CO₂ containing input; (ii) producing a CO₂ feedstream from the captured CO₂; and (iii) reacting the CO₂ feed streamwith a H₂ feed stream to produce a methane containing output.

In one form, the method further includes the step of (iv) separating themethane containing output so as to at least provide methane and a firstwaste output.

In one form, the first waste output is thermally treated to provide CO₂for one of the at least CO₂ containing inputs for step (i).

In one form, one of the at least one CO₂ containing inputs includes air.

In one form, the H₂ feed stream is provided by a water electrolysisprocess.

In one form, water produced during step (iii) is provided for the waterelectrolysis process.

In one form, in step (i), CO₂ is captured using a Calcium Oxide basedcapture process.

In one form, the method further includes the step of: (v) processingmethane from the methane containing output to produce acetylenecontaining output.

In one form, the method further includes the step of (vi) separating theacetylene containing output so as to at least provide acetylene and asecond waste output.

In one form, the second waste output is thermally treated to provide CO₂for one of the at least one CO₂ containing inputs for step (i).

In one form, step (v) includes heating the methane with a thermal plasmareactor.

In one form, the method further includes the step of (vii) processingmethane from the methane containing output to produce a hydrocarboncontaining output.

In one form, the method further includes the step of (viii) separatingthe hydrocarbon containing output so as to at least provide one or morepreselected hydrocarbon products and a second waste output.

In one form, the second waste output is thermally treated to provide oneof the at least one CO₂ containing inputs for step (i).

In one form, step (vii) includes heating the methane, and the methane isheated by a thermal plasma reactor configured such that plasma isprovided in feed with the methane.

In a further broad form the present invention provides a system forcarbon capture and recycling, the system including a CO₂ captureapparatus configured to capture CO₂ from at least one CO₂ containinginput; and a first reactor configured to produce a methane containingoutput from a CO₂ feed stream derived from the CO₂ capture apparatus andan H₂ feed stream.

In one form, the system further includes: a first separator configuredto separate the methane containing output so as to at least providemethane and a first waste output.

In one form the system further includes a thermal treatment apparatusconfigured to treat the first waste output so as to provide CO₂containing input for the CO₂ capture apparatus.

In one from, the CO₂ capture apparatus is configured to capture CO₂ froman air input.

In one form, the system further includes a water electrolysis device forproducing the H₂ feed stream. In one form the water electrolysis deviceis configured to receive water for electrolysis produced in the firstreactor.

In one form, the CO₂ capture apparatus is a Calcium Oxide based captureapparatus.

In one form, the system further includes: a second reactor configured toreceived methane produced in the first reactor and to produce anacetylene containing output therefrom.

In one form the system further includes: a second separator configuredto separate the acetylene containing output so as to at least provideacetylene and a second waste output.

In one from, the second waste output is fed to the thermal treatmentapparatus.

In one form, the second reactor is thermal plasma reactor.

In one from, the system further includes a second reactor configured toreceived methane produced in the first reactor and to produce ahydrocarbon containing output therefrom.

In one form, the system further includes a second separator configuredto separate the hydrocarbon containing output so as to at least providepreselected hydrocarbon products and a second waste output.

In one form, the second waste output is fed to the thermal treatmentapparatus.

In one form, the second reactor is a thermal plasma reactor configuredprovide plasma in feed with the methane.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention may be better understood with reference to theillustrations of embodiments of the invention in which:

FIG. 1 is an overview layout of one example implementation of themethod/system; and

FIG. 2 is an overview of example reactions utilised in one exampleimplementation of the method/system.

FIG. 3 is a flow chart overview of an example implementation of themethod/system.

FIG. 4 is an example of CO₂ capture apparatus.

DETAILED DESCRIPTION

Embodiments of the present invention provide methods and systems forcarbon capture and recycling. Generally, embodiments provide amethod/system for producing hydrocarbons from captured carbon, such as,for example, methane or acetylene. The presently described systemcaptures CO₂, reducing emissions, and produces industrially applicableoutput in the form of common precursor materials that may be furtherprocessed to form a wide range of materials.

In the methods and systems described, carbon dioxide (CO₂) is capturedfrom at least one CO₂ containing input/source. It would be appreciatedthat CO₂ may be recovered/captured from a large range of sources, suchas, for example, from air, incinerator exhaust streams, or industrialplumes etc. It will also be appreciated that CO₂ may be captured using avariety of CO₂ capture devices/systems. In the presently describedsystem/method, CO₂ is typically captured using a calcium oxide (CaO)based apparatus/system. Calcium Oxide (quicklime) based carbon capturedevices/systems have advantages in that the calcium oxide is reusable asa carbon capture agent and permits continuous loop processing as per thebelow reactionsCaO+CO₂→CaCO₃CaCO₃+ΔT→CaO+CO₂

As above, CaO reacts with CO₂ to form Calcium Carbonate, and subsequentheating of the Calcium Carbonate releases the CO₂, providing the CaO forreuse (see Appendix A).

From captured CO₂, a CO₂ feed stream is produced and fed to a methaneproducing reactor in combination with a hydrogen (H₂) feed stream. Amethane containing output is produced by the methane producing reactor.Typically, the methane producing reactor is a conventional batchreactor. It will be appreciated that the H₂ feed stream may also beprovided from a variety of sources. In one example form, H₂ is providedby a water electrolysis process i.e. as per the below reaction2H₂O+e ⁻→2H₂+O₂

The methane containing output form the methane producing reactortypically includes methane, water and other partial products as per thereactionCO₂+4H₂→CH₄+2H₂O

The methane containing output is separated to so as to at least providea substantially pure methane stream and a first waste outputstream/recycle stream. It will also be appreciated that separation ofthe methane containing output may be performed by varying separationdevices/methodologies.

The first waste output, is then typically heated by a thermal treatmentapparatus (e.g. incinerator) to provide additional CO₂ e.g. as per thebelow reaction

${{C_{x}H_{y}} + {\left( {x + \frac{y}{4}} \right)O_{2}}}->{{x{CO}}_{2} + {\frac{y}{2}H_{2}O}}$

The additionally produced CO₂ (e.g. by the incineration of soot etc.)may then be re-fed into the system via carbon capture to drive moremethane production. Additionally, water produced from the production ofmethane may be re-fed to the water electrolysis process to driveproduction of additional H₂. In some examples, excess water may also beused for cooling and steam generated therefrom used to power turbinesetc. Accordingly, it will be appreciated that by products from thereactions at each stage of the process can be re-fed into the system toincrease the conversion efficiency, minimise waste, and maximise themethane produced.

Methane produced may further be fed into an acetylene producing reactorso as to produce acetylene containing output e.g. as per the reactionCH₄+ΔT→C₂H₂

Typically, the reaction requires heating to high temperature (7000-8000°C.). The acetylene producing reactor is thus typically thermal plasmatype reactor, and may, for example be like or similar to the reactors asdescribed in the publication “Thermal Conversion of Methane to AcetyleneFinal Report, J. R. Fincke, R. P. Anderson, T Hyde, R. Wright, R.Bewley, D. C. Haggard, W. D. Swank, Published January 2000, IdahoNational Engineering and Environmental Laboratory, Idaho Falls, Id.83415”.

As with the methane containing output, the acetylene containing outputmay be purified/separated to provide a pure acetylene stream and asecond waste output stream/recycle stream. The second waste outputstream may also be fed back to the thermal treatment apparatus (e.g.incinerator), so as to provide additional CO₂ to be re-fed/re-capturedby the system.

Alternatively or additionally, produced methane may be processed by areactor to provide varied/random hydrocarbon containing output. Thevaried hydrocarbon containing output may then be separated by aseparator preconfigured to separate out preselected hydrocarbons. Thenon-selected output may be provided as a waste output/recycle streamthat may then be re-fed to the thermal treatment apparatus, so as toagain produce additional CO₂ (e.g. by incineration, gasification). Theadditional CO₂ produced being returned for recapture by the carboncapture device/apparatus. The waste output/recycle stream essentiallyprovides a CO₂ containing input for the carbon capture device/apparatus.Again the recycle streams from the reactor provide that the methaneprocessing is energy efficient, with waste minimised.

The reactor in this variation is typically of thermal plasma type whereplasma is provided in feed with the methane. For example, suitablereactors may be as described in the publication “Thermal Conversion ofMethane to Acetylene Final Report, J. R. Fincke, R. P. Anderson, T Hyde,R. Wright, R. Bewley, D. C. Haggard, W. D. Swank, Published January2000, Idaho National Engineering and Environmental Laboratory, IdahoFalls, Id. 83415”.

One example embodiment of the system and method shall now be describedwith reference to FIG. 1.

A carbon capture apparatus (1) is provided which is configured toreceive one or more CO₂ containing inputs/sources. As shown, air may beone of the CO₂ containing inputs. It will also be appreciated a range ofalternate CO₂ containing inputs may be provided such as, for example,waste output streams/recycle streams.

The carbon capture apparatus (1) may take a variety of forms, however,typically, the carbon capture apparatus is a calcium oxide basedapparatus. Furthermore, it will be appreciated that calcium oxide may beutilised for carbon capture in a variety of differently configuredapparatuses.

The carbon capture apparatus (1) is also configured to produce a CO₂feed gas stream for a methane producing reactor (2).

Typically, the calcium oxide based carbon capture apparatus for use withthe present system/method has two preferred configurations. In bothconfigurations, the apparatus typically comprises four chambers with anoutlet (e.g. transport tube) for transporting produced CO₂ feed to amethane producing reactor (2).

In a first configuration, calcium oxide is mixed with air (containingCO₂) in the first chamber via mass transport via air with alternatingfans to maximise dispersion and surfaces exposed to the air. CO₂ iscaptured from the air. In the second chamber, a vacuum is formed, and inthe third chamber, the now calcium carbonate is baked to 700° C. whilstbeing stirred (to speed the process). Carbon dioxide is released andflows through outlet to methane producing reactor. A fourth chambermaintains the vacuum between chambers 2, 3, and 4, before the calciumoxide is reused and air rated once more in chamber 1. This is acontinuous closed loop.

In a second configuration, calcium oxide is hydrated with water in thefirst chamber, with air jets on the bottom bubbling air through themixture while it is pushed along via a spiral configuration. Chamber 2creates a vacuum and then raises the temperature to 400° C. removing thewater, which is fed to chamber 4. In chamber 3, the product is heated to700° C. while being stirred to release the carbon dioxide to the methaneproducing reactor. The calcium oxide is then sent to chamber 4, where itis re-hydrated before returning chamber 1 again. Once again, this is aclosed loop full of calcium oxide.

Another example configuration of a carbon capture described at FIG. 4.

As shown in FIG. 1, H₂ gas is provided to the methane producing reactorto combine with CO₂ feed for the production of methane as per the belowequationCO₂+4H₂→CH₄+2H₂O

It will be appreciated that the reactor (2) provides the appropriateconditions for the production of methane and water from CO₂ and H₂ (e.g.heating at >600° C. at 1 atmosphere of pressure). Typically, the reactoris heated to about 800° C. Typically the methane producing reactor is aconventional batch rector. It will also be appreciated that theefficiency of this process may be improved by adjusting the reactionconditions such as, for example, by increasing the pressure of thesystem and the temperature.

The H₂ feed stream may come from a variety sources. In the example ofFIG. 1, the H₂ feed stream is provided by a water electrolysis device(7) which provides H₂ as per the following equation2H₂O+e ⁻→2H₂+O₂

As water is produced as a by product in the production of methane, thewater can be redirected back to the water electrolysis device (7) forre-use (as shown). In other forms, the water may be used for coolingand/or quenching in subsequent process steps or at other at other partsof the system. Oxygen produced in the electrolysis may be utilised forcleaner combustion in other parts of the system or released to theenvironment. In some forms, the electrolysis reaction is conducted in aU shaped reactor with a simple barrier with the possible addition of anelectrolyte to speed the reaction and lower the energy costs.

A first separator (3) is provided to separate the methane, water andother partial products produced in the methane producing reactor (2).Typically separation is achieved via distillation however it will beappreciated that other methods may be used. Any non-methane andnon-water products are separated out into a first waste output and fedto a thermal treatment apparatus (4). The thermal treatment apparatus istypically an incinerator, although, it will be appreciated that it maytake other forms such as, for example, a gasifier. Thermal treatment,e.g. incineration, results in additional CO₂ product which can then bere-fed to the carbon capture device.

The purified methane from the first separator (3) is directed forfurther processing to an acetylene producing reactor (5). The acetyleneproducing reactor (5) provides appropriate reaction conditions toproduct acetylene form the incoming methane feed stream. Typically, theacetylene is produced via heating as per to the following reactionCH₄+ΔT→C₂H₂

In one form, the reactor is a thermal plasma type reactor. In one form,the reactor utilises argon plasma to provide temperatures of about 8000°C. and rapid quenching follows to produce the acetylene. Examplereactor/process are described in the publication “Thermal Conversion ofMethane to Acetylene Final Report, J. R. Fincke, R. P. Anderson, T Hyde,R. Wright, R. Bewley, D. C. Haggard, W. D. Swank, Published January2000, Idaho National Engineering and Environmental Laboratory, IdahoFalls, Id. 83415”. Typical yields of acetylene are described in AppendixB. In one example, graphite tubing is utilised in the reactor surroundedby heat exchanges to recapture energy to power the argon plasma jets.

A second separator (6) is used to purify the acetylene containingoutput, and provide a second waste output/recycle stream (9). Typicallyseparation is achieved via temperature gradient and/or distillationalthough it will be appreciated a range of appropriate separationmethods may be utilised. As with the first waste output stream, thesecond waste output stream (including soot etc.) is fed to the thermaltreatment apparatus (4) for recycling. CO₂ produced at the thermaltreatment apparatus (e.g. by incineration) is then fed back into thecarbon capture apparatus (1). It will be appreciated that in some forms,heat generated from the thermal treatment apparatus (4) may be used toheat the methane and/or acetylene producing reactors. It is noted thatthe reaction processes in these reactors are exothermic.

Once purified, the acetylene and/or methane produced by thesystem/process can be readily converted via conventional processes intodifferent polymers, benzo aromatics and other organic compounds for usein a wide variety of industrial applications.

In alternate forms, the acetylene producing reactor may be configuredsuch that the argon plasma (or the like) may be provided in-feed withthe methane. This typically results in varied hydrocarbon products beingformed rather than mainly acetylene. It will be appreciated that in suchexamples, the second separator (6) would be configured to filterpreselected hydrocarbon products. The remaining non-selected productswould be re-fed to the thermal treatment apparatus (e.g. incinerator)for recycling. Again any produced CO₂ from combustion/gasification mayre-captured for further methane production.

The presently described system/method has significant advantages overconventional carbon capture and storage approaches for reducing CO₂emissions. In particular, there are minimal waste products as therecycle feeds (i.e. waste output streams) push the conversion ratetowards 100%.

In addition, once purified, acetylene has many industrial applicationsand can be further processed and converted, for example, into differentpolymers, benzo aromatics and other organic compounds. Methane may alsobe extracted from the system to produce compounds other than thoseproduced by reacting acetylene.

It will be appreciated that power for the various components/reactionsmay be provided/supplemented by mains electricity, renewable energysources and waste combustion.

In particular, it will be appreciated that due to the configuration ofthe system, organic waste material can be directly combusted (e.g. inthe thermal treatment apparatus) and filtered to provide the CO₂ for thecarbon capture. Furthermore, the heat from the combustion also may besupplied to the methane and acetylene producing reactors.

Furthermore, as the methane and acetylene producing reactors are runningexothermic processes, once heated, excess energy therefrom may beutilised to further provide electrical energy to the system, whileenergy recycling may also be used on the coolant for the argon plasmajets. Excess energy may also be harvested by steam turbines to power theargon plasma reactions.

Optional embodiments of the present invention may also be said tobroadly consist in the parts, elements and features referred to orindicated herein, individually or collectively, in any or allcombinations of two or more of the parts, elements or features, andwherein specific integers are mentioned herein which have knownequivalents in the art to which the invention relates, such knownequivalents are deemed to be incorporated herein as if individually setforth.

Although a preferred embodiment has been described in detail, it shouldbe understood that various changes, substitutions, and alterations canbe made by one of ordinary skill in the art without departing from thescope of the present invention.

It will be appreciated that various forms of the invention may be usedindividually or in combination.

APPENDIX A

Calcium oxide is usually made by the thermal decomposition of materials,such as limestone or seashells, that contain calcium carbonate (CaCO3;mineral calcite) in a lime kiln. This is accomplished by heating thematerial to above 825° C. (1,517° F.), [6] a process called calcinationor lime-burning, to liberate a molecule of carbon dioxide (CO2), leavingquicklime.CaCO3(s)→CaO(s)+CO2(g)

The quicklime is not stable and, when cooled, will spontaneously reactwith CO₂ from the air until, after enough time, it will be completelyconverted back to calcium carbonate unless slaked with water to set aslime plaster or lime mortar.

APPENDIX B Conver- Maximum Hydrocarbon Minimum sion Acetylene Yieldother Normalized SER kW- Reactor Feed- Plasma Quench Effi- Yield thanAcetylene Acetylene Soot hr/k_(g) - Reference Year Process Size stockGas Method ciency y_(C2H2) y_(HC) Yield y_(C2H2) Yield C₂H₂ Leutner &1961 DC 6.8 kW CH₄ Ar Wall 92.9%  80.1 not 86.2 5.7% 72.5 Stokes plasmaheat analyzed jet transfer Gladisch 1962 Huels 8 MW natural CH₄ Water70.5%  51.4%  45.9% 72.9%  2.7% 12.1 DC arc gas spray Anderson 1962 DC<10 kW CH₄ H₂ Water >90% 76% not 88% not 9.16 & Case plasma sprayanalyzed analyzed jet Holmes 1969 DuPont 9 MW CH₄ H₂ not not 70% not not8.8 DC arc reported reported reported reported Ibberson 1976 DC <10 kWCH₄ Ar Wall >90% 82% not 91% not 9.0 & Sen plasma heat reported analyzedjet transfer Plotczyk 1983 DC 10-40 kW CH₄ H₂ Wall  95% 80% not 84% not15.5 plasma heat analyzed analyzed jet transfer Kovener 1983 RF 4 kW CH₄& He Wall not not not — not 88 plasma natural heat reported reportedreported reported gas transfer Plotczyk 1985 DC 4-16 kW CH₄ Ar Wall >90%86% not 95% not 23.9 plasma heat reported reported jet transfer

The invention claimed is:
 1. A method for recycling CO₂ from CO₂containing inputs to produce hydrocarbon products, the method includingthe steps of: (i) capturing CO₂ from at least one CO₂ containing input,wherein one of the at least one CO₂ containing input includes air; (ii)producing a CO₂ feed stream from the captured CO₂; (iii) reacting theCO₂ feed stream with a H₂ feed stream to produce a methane containingoutput; (iv) separating the methane containing output so as to at leastprovide methane and a first waste output, wherein the first waste outputis incinerated or gasified to provide one of the at least one CO₂containing inputs for step (i); (v) processing methane from the methanecontaining output to produce an acetylene containing output; and (vi)separating the acetylene containing output so as to at least provideacetylene and a second waste output.
 2. A method as claimed in claim 1,wherein one of the at least one CO₂ containing inputs is derived fromincinerator exhaust streams or industrial plumes.
 3. A method as claimedin claim 1, wherein the H₂ feed stream is provided by a waterelectrolysis process.
 4. A method as claim in claim 3, wherein waterproduced during step (iii) is provided for the water electrolysisprocess.
 5. A method as claimed in claim 1 wherein, in step (i), CO₂ iscaptured using a Calcium Oxide sorbent.
 6. A method as claimed in claim1, wherein the second waste output is incinerated or gasified to provideone of the at least one CO₂ containing inputs for step (i).
 7. A methodas claimed in claim 6, wherein step (v) includes heating the methanewith a thermal plasma reactor.
 8. A method as claimed in claim 1,further including the step of (v) heating methane from the methanecontaining output with a thermal plasma reactor to produce a hydrocarboncontaining output, wherein the thermal plasma reactor is configured suchthat plasma is provided in feed with the methane.
 9. A method a claimedin claim 8, further including the step of (vi) separating thehydrocarbon containing output so as to at least provide one or morepreselected hydrocarbon products and a second waste output.
 10. A methodas claimed in claim 9, wherein the second waste output is incinerated orgasified to provide one of the at least one CO₂ containing inputs forstep (i).